Bipolar disorder and medical comorbidities: A Portuguese population-based observational retrospective study...

This study aimed to use the Charlson Comorbidity Index (CCI) to assess the prevalence of medical comorbidities among hospitalization episodes with a primary Bipolar Disorder (BD) diagnosis, and to analyze its association with hospitalization outcomes.

A population-based observational retrospective study was conducted using a Portuguese administrative database containing all mainland public hospitalizations. From 2008-2015, hospitalization episodes with a primary diagnosis of BD were analysed. Outcomes included: length of stay (LoS), in-hospital mortality and discharge destination.

Overall, 20807 hospitalization episodes were analysed. Mean±standard deviation age at admission was 47.9±14.3 years, and these episodes mostly refer to women's admissions (66.6%). Median (1st quartile; 3rd quartile) LoS was 16.0 (9.0; 25.0) days. A total of 2145 (10.3%) episodes had ≥1 CCI comorbidities registered, being diabetes the most prevalent. LoS was significantly higher for episodes with secondary diagnoses of congestive heart failure, cerebrovascular disease, dementia, diabetes, renal disease and malignancy (all p<0.05). Episodes with a registry of myocardial infarction, peripheral vascular disease, malignancy and renal disease diagnoses had higher in-hospital mortality.

Limitations include the use of data registered for administrative reasons rather than research purposes, and the analysis of hospitalization episodes, instead of patients.

In this Portuguese nationwide study, greater comorbidity had a measurable impact on BD hospitalization outcomes. During the study period the prevalence of CCI comorbidities rose from 8.1% to 17.4%, which may reflect the overall increasing quality of hospital-coded data in Portugal throughout the years. The detection and timely management of medical comorbid conditions will likely prevent the high BD medical burden.